To regard, as a charged member, a charged body on which a static electricity is charged, and to spray ionized air onto the charged member to remove the static electricity from the charged member, an ion generator called also an ionizer or static-electricity-removing device has been used. For example, the ion generator used in manufacture lines of manufacture or assembly of electronic parts has been used, by regarding electronic parts or manufacture assembly jigs etc. as charged members, to remove the static electricity of the charged member that has been charged. By spraying the ionized air on the charged member, it is possible to prevent foreign substances from adhering to the electronic parts etc. due to the static electricity, or the electronic parts from being destroyed or adhering to the jigs due to the static electricity.
The ion generator utilized for use applications as described above has a needle-like discharge electrode, and a cylindrical opposite electrode. The opposite electrode has a through hole that guides air, and constitutes a nozzle that sprays the ionized air onto the charged member, and the discharge electrode is disposed at a center of a base end portion of the opposite electrode serving as the nozzle. When an AC high voltage is applied between the discharge electrode and the opposite electrode under a state of supplying air to the discharge electrode, corona discharges occur around the discharge electrode, and the supplied air is ionized. The ionized air is sprayed onto the charged member from the nozzle serving as the opposite electrode.
The discharge electrode is not only subjected to abrasion due to air plasmanized by the corona discharges, but also does not avoid adhesion of dust, and once the dust adheres to the discharge electrode, efficiency of ion generation is reduced. For this reason, the discharge electrode is detachably mounted onto an ion generator main body, and by doing maintenance of the discharge electrode periodically, a replacing operation or cleaning operation of the discharge electrode is performed.
As a type of mounting the discharge electrode onto the generator main body, as disclosed in Patent Document 1 (Japanese Patent No. 4170844), there is a type in which a discharge electrode attached to a holder is detached, with respect of a head portion of a main body case, from its back side. The head portion is attached to a nozzle, i.e., an opposite electrode fixed to an attachment bracket. Patent Document 2 (Japanese Patent Application Laid-Open Publication No. 2008-198533) discloses an ionizer in which: an electrode needle cartridge into which a discharge electrode and a high-voltage generator are incorporated is detachably mounted in a main body block; and a nozzle is fixed to the main body block. Further, Patent Document 3 (Japanese Patent Application Laid-Open Publication No. 2004-362951) discloses an ionizer in which: an air pipe supplying air is connected to a discharge unit provided with a discharge electrode; and an opposite electrode unit is assembled into an ionizer main body in which the discharge unit is detachably mounted. In the ionizers as mentioned in above Patent Documents, the discharge electrode is detached from the back side with respect to the opposite electrode serving as the nozzle.
In contrast, Patent Document 4 (Japanese Patent Application Laid-Open Publication No. 2006-100248) discloses an ionizer of such a type that a holder into which a discharge electrode is press-inserted is incorporated inside a hollow axial-body portion, and that a cylindrical opposite electrode is screwed outside the holder. The discharge electrode and the opposite electrode are detached from a front side.
The discharge electrode is disposed at a center of a base end portion of the opposite electrode serving as the nozzle, and if the discharge electrode is disposed so as to directly oppose the opposite electrode, since the air plasmanized by the corona discharges contacts directly with an inner circumferential surface of the opposite electrode made of a conductive material, the inner circumferential surface of the opposite electrode is subjected to abrasion. For this reason, incorporated into the inner circumferential surface of the opposite electrode is an insulative sleeve made of an insulative material having a plasma-proof property such as ceramic. Since dust adheres also to this inner circumferential surface of the sleeve, the dust adhering to the sleeve needs to be removed periodically.
However, conventionally, there has been a problem in that in the ion generator in form of fixing the sleeve to the nozzle, the discharge and opposite electrodes are each detached from the device main body in order to remove the dust adhering to the discharge electrode and sleeve, whereby a maintenance operation of the ion generator cannot be easily performed. For example, since the electrically insulative sleeve disclosed in Patent Document 2 is fixed to the nozzle, cleaning of the sleeve needs to remove the discharge needle cartridge from the main body block. In addition, although the nozzles different in shape according to a kind of the charged member are often mounted to the same ion generator at a time of maintenance, when the sleeve is incorporated inside the nozzle serving as the opposite electrode, the sleeve needs to be provided to each of a plurality of kinds of nozzles, and replacement of the nozzle only cannot be made.
An object of the present invention is to be able to detach simply a sleeve, which is disposed between a discharge electrode and an opposite electrode and made of an insulative material, and which can easily perform a maintenance operation of an ion generator.
An object of the present invention is to be able to replace easily the opposite electrode without removing the sleeve, and to use selectively the opposite electrodes having various kinds of shapes.